<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript注释</title>
</head>

<body>
    <h2>JavaScript 注释<b>不会</b>被执行。</h2>
    <p id="demo"></p>
    <script>
        var x;
        x = 7;
        // x = 8; 我不会被执行
        document.getElementById("demo").innerHTML = x;
    </script>
</body>
</html>